Light reflectors (e.g., for bikes) are also made out of many little corners to reflect the light to its source. For sound, it should be the same with a corner

Light reflectors (e.g., for bikes) are also made out of many little corners to reflect the light to its source. For sound, it should be the same with a corner of a room, it ~doubles the sound in the vicinity of the corner, hence a ~3dB increase